The use and impact of cancer medicines in routine clinical care: methods and observations in a cohort of elderly Australians

Are clinical trial eligibility criteria representative of older patients with lung cancer? A population-based data linkage study

OBJECTIVES

Older adults constitute the majority of patients with lung cancer. However, they are under-represented in clinical trials as eligibility criteria often restrict enrolment based on comorbidities that are common with aging. We aimed to describe comorbidities relating to trial exclusion criteria in older adults with lung cancer, determine the proportion that would typically be excluded from trials, and examine the impact on treatment uptake.

MATERIALS AND METHODS

We conducted a population-based study of people aged ≥65 years diagnosed with metastatic lung cancer using linked data for clients of the Australian Government Department of Veterans' Affairs (2005-2015). We defined trial-typical patients based on the absence of comorbidities related to the following: inadequate organ (cardiac, renal, hepatic, marrow) function; cognitive dysfunction; poor performance status (PS); prior malignancy within 5 years. We report systemic therapy uptake within 3 months of diagnosis.

RESULTS

Our study included 677 patients (median age 84). Over half (53.4%) were not trial-typical, with the most common reasons being poor PS (37.5%), cardiac disease (19.2%), and prior cancer (12.9%). Eighty-two (12.1%) received systemic therapy. Patients with poor PS, cardiac disease, and dementia had lower treatment uptake rates. However, there was no significant difference in treatment uptake between trial-typical and non-trial-typical patients (13.4 vs 11.0%).

CONCLUSION

More than half of older adults with advanced lung cancer would be typically excluded from trial participation. Future clinical trials of older adults need to consider broader eligibility criteria to better reflect this population to gain the best evidence for their care.

Patterns of opioid use in older people diagnosed with cancer in New South Wales, Australia

PURPOSE

Opioids provide effective analgesia for most cancer patients, but little is known about individual-level opioid use after cancer diagnosis. We examined the patterns of and factors associated with opioid use in older people diagnosed with cancer.

METHODS

We used the Department of Veterans' Affairs (DVA) client data linked with the New South Wales (NSW) Cancer Registry and the Repatriation Pharmaceutical Benefits Scheme data. We included people aged ≥65 years diagnosed with cancer in NSW, Australia in 2005 to 2015. We examined patterns of opioid use in the 12 months after cancer diagnosis and used cause-specific hazards models to examine factors associated with opioid use.

RESULTS

Of 13 527 people diagnosed with cancer, 51% were dispensed opioids after their diagnosis. We observed the highest proportions of use in people diagnosed with pancreas, liver, or lung cancers. Opioid use was associated with female sex, younger age, more advanced degree of cancer spread, opioid use before cancer diagnosis, and multimorbidity. Forty-four percentages of all people dispensed opioids had a history of opioid use in the 12 months before their cancer diagnosis; these people had higher median number of different opioids and opioid dispensings, and a shorter time to first opioid dispensing than opioid-naive people.

CONCLUSION

Our study suggests that many older cancer patients were dispensed opioids before their cancer diagnosis. Previously opioid-treated people had more intense opioid use patterns after diagnosis than opioid-naïve people. Acknowledging the history of opioid use is important as it may complicate pain treatment in clinical practice.

Risk of squamous cell carcinoma of the lip and cutaneous melanoma in older Australians using hydrochlorothiazide: A population-based case-control study

Recent European and US studies reported increased risks of skin cancers associated with hydrochlorothiazide (HCTZ) treatment. Our study aimed to determine the risk of lip cancer and malignant melanoma among Australians prescribed HCTZ. We conducted a case-control study nested within a population of veterans residing in New South Wales in 2004-2015, using Australian Department of Veterans' Affairs data linked with cancer registrations, hospitalisation and prescription dispensings. Among DVA healthcare card holders 65 years and older, we identified incident cases of squamous cell carcinoma of the lip and of cutaneous melanoma, each matched with up to 20 controls through risk-set sampling. We estimated odds ratios (ORs) associating HCTZ use with each cancer using conditional logistic regression, adjusting for predefined confounders. For lip cancer (45 cases), ever-use of HCTZ yielded an OR of 2.6 (95% CI: 1.4-5.0) and high HCTZ use (≥25 000 mg) an OR of 4.7 (95% CI: 1.6-13.7). For cutaneous melanoma (659 cases), ever-use of HCTZ resulted in an OR of 1.2 (95% CI 1.0-1.5) and high HCTZ use in an OR of 1.2 (95% CI: 0.8-1.8). Our findings align with risk estimates from previous studies and provide further evidence that HCTZ's photosensitising properties may promote carcinogenesis in sun-exposed tissues.

Patterns of oxycodone controlled release use in older people with cancer following public subsidy of oxycodone/naloxone formulations: An Australian population-based study

AIM

Public subsidy of the oxycodone/naloxone controlled release (CR) combination in December 2011 expanded the overall market for oxycodone CR in the general public in Australia; we evaluate its impact in people with cancer.

METHODS

We used Repatriation Pharmaceutical Benefits dispensing data linked with the NSW Cancer Registry for Department of Veterans' Affairs (DVA) healthcare card holders 65 years and older residing in NSW between 2004 and 2013 to identify clients with cancer and their opioid dispensings. We used interrupted time series analysis to model changes in monthly rates of oxycodone CR tablets dispensed and initiations. We performed a retrospective cohort study to examine changes in client characteristics and opioid utilization over time by comparing clients initiating oxycodone CR before and after subsidy.

RESULTS

The rate of oxycodone CR tablets dispensed/month increased by 20% from December 2011, due to uptake of the oxycodone/naloxone CR combination; monthly initiations increased immediately by 17%. Initiations of buprenorphine, fentanyl, and morphine declined from December 2011. DVA healthcare card holders were significantly more likely to initiate the 5 mg oxycodone CR formulation; more likely to use immediate release oxycodone in the 90 days following initiation; and less likely to use a weak opioid in the 90 days preceding oxycodone CR initiation following December 2011 than they were prior to that time.

CONCLUSIONS

The public subsidy of the oxycodone/naloxone CR formulation expanded the overall oxycodone CR market for DVA healthcare card holders with cancer. Our findings highlight the need for updated guidelines around risk management for opioid treatment in patients with cancer.

Identifying incident cancer cases in dispensing claims: A validation study using Australia's Repatriation Pharmaceutical Benefits Scheme (PBS) data

Introduction

Dispensing claims are used commonly as proxy measures in pharmacoepidemiological studies; however, their validity is often untested.

Objectives

To assess the performance of a proxy for identifying cancer cases based on the dispensing of anticancer medicines and estimate the misclassification of cancer status and potential for bias researchers may encounter when using this proxy.

Methods

We conducted our validation study using Department of Veterans’ Affairs (DVA) client data linked with the New South Wales (NSW) Cancer Registry and Repatriation Pharmaceutical Benefits Scheme data. We included DVA clients aged ≥65 years residing in NSW between July 2004 and December 2012. We matched clients with a cancer diagnosis to clients without a diagnosis based on demographic characteristics and available observation time. We used dispensing claims for anticancer medicines dispensed between July 2004 and December 2013 as a proxy to identify clients with cancer and calculated sensitivity, specificity, positive predictive values and negative predictive values compared with cancer registrations (gold standard), overall and by cancer site. We illustrated misclassification by the proxy in a cohort of people initiating opioid therapy. Using the proxy, we excluded people with cancer from the cohort, in an attempt to delineate people potentially using opioids for cancer rather than chronic non-cancer pain.

Results

We identified 15,679 new cancer diagnoses in 14,112 DVA clients from the cancer registry and 62,663 clients without a diagnosis. Sensitivity of the proxy based on dispensing claims was 30% for all cancers and around 20% for specific cancers (range: 10-67%). Specificity was above 90% for all cancers. The dispensing proxy correctly identified 26% of people with a cancer diagnosis who initiated opioid therapy and failed to identify 74% those with a cancer diagnosis; the proxy was most robust for clients with breast cancer where 61% were correctly identified by proxy.

Conclusions

Using dispensing of anticancer medicines to identify people with a cancer diagnosis performed poorly. Excluding patients with evidence of anticancer medicine use from cohort studies may result removal of a disproportionate number of women with breast cancer. Researchers excluding or otherwise using anticancer medicine dispensing to identify people with cancer in pharmacoepidemiological studies should acknowledge the potential biases introduced to their findings.

Keywords

cancer, diagnosis, proxy, dispensing records, validation study

Health service use and costs in the last 6 months of life in elderly decedents with a history of cancer: a comprehensive analysis from a health payer perspective

Background:

There is growing interest in end-of-life care in cancer patients. We aim to characterise health service use and costs in decedents with cancer history and examine factors associated with resource use and costs at life's end.

Methods:

We used routinely collected claims data to quantify health service use and associated costs in two cohorts of elderly Australians diagnosed with cancer: one cohort died from cancer (n=4271) and the other from non-cancer causes (n=3072). We used negative binomial regression to examine the factors associated with these outcomes.

Results:

Those who died from cancer had significantly higher rates of hospitalisations and medicine use but lower rates of emergency department use than those who died from non-cancer causes. Overall health care costs were significantly higher in those who died from cancer than those dying from other causes; and 40% of costs were expended in the last month of life.

Conclusions:

We analysed health services use and costs from a payer perspective, and highlight important differences in patterns of care by cause of death in patients with a cancer history. In particular, there are growing numbers of highly complex patients approaching the end of life and the heterogeneity of these populations may present challenges for effective health service delivery.

Health service utilisation and investigations before diagnosis of cancer of unknown primary (CUP): A population-based nested case-control study in Australian Government Department of Veterans' Affairs clients

BACKGROUND

Population-based data on the use of health services and diagnostic investigations for patients with cancer of unknown primary (CUP) is scarce. It is uncertain whether the pathways to diagnosis are different for CUP compared to other cancers.

METHODS

We performed a population-based nested matched case-control study using linked routinely collected records for Australian Government Department of Veterans' Affairs clients, 2004-2007. We compared health care consultations, hospitalisations, emergency department visits, and diagnostic procedures in the three months prior and the month of diagnosis for 281 clients registered with a diagnosis of CUP (C809) and 1102 controls randomly selected from clients registered with a first diagnosis of metastatic cancer of known primary.

RESULTS

Overall, the median age at cancer diagnosis was 83 years. CUP patients were slightly older and had significantly more comorbidities prior to diagnosis than those with known primary. Compared to known primary, a diagnosis of CUP was significantly more likely after an emergency department visit, less specialist input, fewer invasive diagnostic procedures such as resection or endoscopy, and more non-invasive procedures such as magnetic resonance imaging. There were no differences in primary care or allied health consultations and hospitalisations.

CONCLUSIONS

This health care pathway suggests delayed recognition of cancer and scope for improvement in the medical management of high-risk individuals presenting to primary care. The pattern of diagnostic investigations reveals under-investigation in some CUP patients but this is likely to reflect recognition of limited treatment options and poor prognosis and is consistent with clinical guidelines.